The present disclosure generally relates to process pressure measurement. More specifically, but not by limitation, the present disclosure relates to pressure transmitter assemblies with mechanical features configured to support multiple pressure ratings.
There are currently a wide variety of process environments. Process environments can include one or more systems that provide a process variable as an informative output. The term process variable generally refers to feature of a process, such a chemical or physical feature, that can change based on a variety of factors within the process. Examples of process variables can include pressure, temperature, flow, conductivity, pH, and other properties. One goal of monitoring a process environment is to obtain a process measurement. For instance, pressure is considered to be a basic process variable that is used for the measurement of flow, which is generally the difference of two pressures.
In order to obtain a process measurement, many process environments include a process transmitter. Process transmitters usually include a sensor that responds to a measured process variable with a sensing element. The sensing element converts the variable to a standardized transmission signal as an output for recordation and/or control. Industrial process transmitters can be used to measure a variety of process variables in a variety of process environments including, but not limited to, industrial processes such as slurries, liquids, vapors and gases in chemical, pulp, petroleum, gas, pharmaceutical, food and other processing plants. One particular type of process transmitter includes a fluid pressure transmitter.
Pressure transmitters are typically coupled to a process by virtue of a manifold. As such, a manifold can be an assembly between a process and a transmitter that carries a process fluid though one or more channels to the transmitter for measurement. Manifolds can include a variety of channel configurations including those found in integral manifolds, conventional manifolds, inline manifolds, and/or coplanar manifolds. As an example, manifolds and their associated channel configurations can include those available from Rosemount Inc. of Chanhassen, Minn. under the trade designations Model 304, Model 305 and Model 306 manifolds.
Each channel of the manifold may be opened or closed by a valve assembly to control the flow of the process fluid. Valve assemblies generally operate to isolate a process sample, equalize a process flow, and/or vent or drain a fluid flow from the process. Coplanar manifolds, in particular, can have any number of valves such as those with two, three, or five valve configurations. Manifolds typically have at least one valve that provides pressure transmitter isolation. For instance, an isolation valve will be actuated to open or close a fluid channel to a sample chamber or to another area within the manifold that leads to a pressure sensor.
The particular type of manifold that is used for a process may depend on several factors. For one, it may depend on the type of process fluid that is being sampled. For example, chemical solutions may be more suited for a coplanar manifold while water-based solutions are more suited for an integral manifold. More importantly, however, the selection of a manifold and its associated components, such as a valve assembly, may depend on the pressure of the process fluid. In some process environments, there are two primary pressure ratings for manifold assemblies. These include a low pressure rating of 6,092 pounds per square inch (PSI), and a high pressure rating of 10,000 PSI or higher. In addition, some industry standards require that the products be tested at a much higher pressure rating than that which will be produced by the process. For example, some products must pass qualification at four times the pressure rating that is observed in the process.